1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer that forms an electrostatic image on an image bearing member, for example, by an electrophotographic system, an electrostatic recording system and the like to convert the electrostatic image into a visible image (toner image) by a developer contained in a developing device. In particular, the invention relates to an image forming apparatus to which the developer is replenished by rotation of a developer replenishment container, and a developer replenishing apparatus.
2. Description of the Related Art
An image forming apparatus, in which a developer (toner) is supplied to a developing device by rotating a cylindrical developer replenishment container in a laying-down state, has been put to practical use.
The presence or absence of the developer is determined by a developer detection sensor provided in a developer accommodation portion of a developer replenishing apparatus included in the image forming apparatus, and the enough developer to be used in the developing device is supplied from the developer replenishing apparatus. When the developer in the developer accommodation portion decreases, the “absence of developer” is determined by the developer detection sensor, and the developer replenishment container rotates. When the developer replenishment container rotates, the developer is replenished to the developer replenishing apparatus from a discharge opening portion, and when “the presence of developer” is determined by the developer detection sensor, the rotation of the developer replenishment container stops. During the replenishment operation of the developer, the developer replenishment container is continuously rotating.
Japanese Patent Laid-Open No. 2010-210946 discloses a configuration that has a discharge opening portion with an inner diameter smaller than an accommodation portion at one end portion of a cylindrical developer replenishment container, a developer in the developer replenishment container moves to the discharge opening portion side in accordance with the rotation of the developer replenishment container, and then the developer in the developer replenishment container is scooped up and conveyed to the discharge opening portion, by a conveying portion which rotates integrally with the developer replenishment container. By having the conveying portion, the developer remaining inside the container is reduced, without exceeding the height of the discharge opening portion.
In the configuration in which toner is scooped up and conveyed to the discharge opening portion by the conveying portion which rotates integrally with the cylindrical container as described above, the conveying portion has roles (a) and (b) described below. That is, there are (a) a role of scooping the developer accumulated near the discharge opening portion by a scooping portion, and (b) a role of conveying the scooped developer to the discharge opening portion, by sliding down a guide portion due to the own weight of the developer.
Moreover, in a case where the conveying portion rotates as described above, the developer existing in the container during a replenishment operation is broadly divided into (1) a developer that is scooped up and conveyed to the discharge opening portion by the conveying portion, and (2) a developer that remains in the container and is not conveyed to the discharge opening portion.
When classifying the developer described in (2), although the developer is scooped up by the conveying portion, there are a spilled developer, a developer that spills, rebounds, and floats in the container again, and a developer that starts to float by the impact of the spilled developer.
In the developer replenishment container having the conveying portion that scoops up the developer within the container as described above, when there is a large quantity of developer in the container, there is also a large quantity of developer accumulated in the discharge opening portion. Thus, it is possible to scoop up a lot of developer by one scooping operation (the role (a) of the conveying portion). Since the scooped developer slides down the guide portion and is conveyed at this time, a quantity of discharge also increases (the role (b) of the conveying portion). Since the scooping operation per unit time and the number of times, in which the developer slides down and is discharged, increase by performing the replenishment operation by the continuous rotation, the quantity of discharge increases. When the quantity of developer in the developer replenishment container is large, discharging properties are satisfactory by performing the replenishment operation by the continuous rotation.
On the other hand, when the quantity of developer in the container is small, that is, when there are many hollow portions inside the container, if the replenishment operation is continuously performed, the developer in the container is constantly stirred by the rotation of the container main body and the conveying portion, and thus a quantity of floating developer increases. As a result, since the quantity of developer to be scooped up by the scooping operation decreases, and the quantity of developer that slides down and is conveyed also decreases, discharging properties are lowered, and the quantity of developer remaining inside the container increases. Further, since the quantity of floating developer is unstable, the quantity of developer remaining inside the container varies. The increase and the variation of quantity of developer remaining inside the container become a problem because it leads to an increase in running costs.